Question 1

Which of the following best describes the structure of the plasma membrane according to the fluid mosaic model?

Accepted Answer

A double layer of phospholipids with embedded proteins that can move laterally, and carbohydrates attached to the outer surface.

Question 2

A red blood cell is placed in a solution and begins to shrink. Which of the following best describes the tonicity of the solution and the direction of water movement?

Accepted Answer

The solution is hypertonic; water moves out of the cell.

Question 3

Which of the following is a function of integral membrane proteins?

Accepted Answer

Acting as transport channels, receptors for signal transduction, and enzymes.

Question 4

Which process requires energy in the form of ATP to move substances across the plasma membrane against their concentration gradient?

Accepted Answer

Primary active transport

Question 5

A patient with severe burns loses large amounts of fluids and ions from damaged cells. Which property of the plasma membrane is compromised in this scenario?

Accepted Answer

Selective permeability

Question 6

Which of the following best explains why oxygen and carbon dioxide can diffuse directly through the plasma membrane?

Accepted Answer

They are nonpolar and lipid-soluble.

Question 7

Which type of cell junction prevents the passage of molecules and ions through the space between adjacent cells, creating distinct compartments?

Accepted Answer

Tight junctions

Question 8

The sodium-potassium pump moves ions across the plasma membrane. For each ATP molecule hydrolyzed, how many sodium and potassium ions are transported, and in which directions?

Accepted Answer

$$3 Na$^+$$ out, $$2 K$^+ in$$

Question 9

Which of the following best describes the role of the glycocalyx in cell biology?

Accepted Answer

It serves as a biological marker for cell-to-cell recognition and helps the immune system distinguish self from nonself.

Question 10

A cell is placed in a solution with lower osmolarity than its cytoplasm. What will happen to the cell, and what is this process called?

Accepted Answer

The cell will swell and may burst; this is called lysis.

Question 11

Which of the following is true regarding facilitated diffusion?

Accepted Answer

It uses carrier or channel proteins to move substances down their concentration gradient.

Question 12

Which organelle is responsible for producing most of the cell’s ATP via aerobic respiration and contains its own DNA and ribosomes?

Accepted Answer

Mitochondrion

Question 13

Which cytoskeletal element is primarily responsible for resisting pulling forces and is composed of tough, insoluble protein fibers?

Accepted Answer

Intermediate filaments

Question 14

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

It selectively brings specific molecules into the cell by binding to receptors on the plasma membrane.

Question 15

Which of the following statements about the resting membrane potential (RMP) is correct?

Accepted Answer

RMP is typically negative inside the cell due to the movement of K$$^+$$ out and the relative impermeability to Na$$^+.$$

Question 16

Which of the following is a function of the Golgi apparatus?

Accepted Answer

Modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles.

Question 17

Which of the following best explains why lysosomal storage diseases, such as Tay-Sachs disease, are so damaging to nerve cells?

Accepted Answer

Lysosomes lack specific enzymes, causing accumulation of undigested substances that interfere with cell function.

Question 18

Which of the following is a correct sequence of events during mitosis?

Accepted Answer

Prophase, Metaphase, Anaphase, Telophase

Question 19

Which of the following best describes the role of tRNA during translation?

Accepted Answer

It brings specific amino acids to the ribosome based on the codon sequence of mRNA.

Question 20

Which of the following is a real-world application of the central dogma of molecular biology (DNA → RNA → Protein) in modern medicine?

Accepted Answer

The use of mRNA vaccines to instruct cells to produce viral proteins, triggering an immune response.

Cells: The Living Units – Structure, Function, and Membrane Transport

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